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7/5/2013 11:45 P.M. ET

Former Nat Marquis has fond memories of Washington

WASHINGTON -- Padres right-hander Jason Marquis, who pitched for the Nationals from 2010-11, returned to Nationals Park for the first time since then on Friday for the opener of a three-game series. He will start against his former club on Saturday.

Marquis was with the Nationals during a period of transition. They went 69-93 in 2010 and 80-81 the next year, during which Davey Johnson took over managerial duties from Jim Riggleman. Based on what he saw during that time, Marquis wasn't too surprised Washington broke out last year.

"To me, winning starts with pitching. Pitching and defense," Marquis said. "You throw guys like [Jordan Zimmermann], [Stephen] Strasburg, you traded for Gio Gonzalez -- when you throw those guys out there every five days, your chances of winning go through the roof. They've done a quality job of getting good young arms through the organization and outside the organization.

"Those pitchers have succeeded pretty well, and hopefully they lose three games here the next three days and then go back to winning."

Marquis said he "had a blast" while with Washington, where he signed as a free agent. Injuries limited the veteran to 13 ineffective starts that first year, when he went 2-9 with a 6.60 ERA. But he went 8-5 with a 3.95 ERA in '11, then was dealt to the D-backs just before the non-waiver Trade Deadline for Minor League shortstop Zach Walters, Washington's No. 13 prospect who is now at Triple-A Syracuse.

Marquis, 9-4 with a 3.74 ERA this season, remains in touch with some Nationals players and staff members. He said "it's fun to watch" how the team's young pitchers have developed and also spoke glowingly of catcher Wilson Ramos.

The two worked together after the Nationals acquired Ramos from the Twins in a July 2010 Deadline deal that sent Matt Capps to Minnesota. Ramos had a breakout year in '11, but since then has dealt with a kidnapping ordeal in his native Venezuela and an array of injuries.

"I loved throwing to him," Marquis said. "He was one of my favorite guys to throw to that I've been in the big leagues with, and he's strong as an ox. That guy's going to run into 20 home runs if he can stay healthy. That's just how strong he is. I think he can handle a big league staff with the best of them and he's got good guys to do that with."

Johnson likely resting Harper for rest of Padres series

WASHINGTON -- Nationals manager Davey Johnson said after Friday's 8-5 win over the Padres that struggling left fielder Bryce Harper is "grinding too hard," and likely will be out of the lineup for the next two games.

"I'll probably give Harper a couple days off," Johnson said. "I think he's just fighting himself."

Harper went 0-for-4 with a sacrifice fly and a strikeout on Friday, making him 0-for-18 since he hit a home run in his first at-bat off the disabled list on Monday against the Brewers. He has three walks and seven strikeouts over that span.

Johnson believes Harper's issues are probably both mental and physical. The 20-year-old missed a little more than a month with bursitis in his left knee, then completed a four-game Minor League rehab stint before returning to the Nationals.

"He's just … coming back from the long layoff, I think hadn't had much break when he came back," Johnson said. "I just need to back off him a little bit."

Harper has registered some good at-bats over the past few games. On Tuesday, Brewers center fielder Carlos Gomez twice robbed him of hits with highlight-reel catches, including one at the warning track. Harper walked twice on Thursday, and in his second at-bat on Friday, he hit a fly ball to the warning track in center to drive in a run.

But in his final three at-bats on Friday, Harper saw a total of six pitches, including a strikeout. His average has dropped to a season-low .260.

Mattheus could start rehab assignment in 10 days

WASHINGTON -- Nationals reliever Ryan Mattheus threw off a mound on Friday for the first time since breaking his pitching hand, and manager Davey Johnson said the right-hander could begin a Minor League rehab assignment in about 10 days.

Mattheus suffered the injury on May 19 in San Diego, when he punched a locker after giving up five runs in an inning of work, by far his worst performance of the season. He already had been throwing off flat ground, and before Friday's series opener against the Padres, he made 25 tosses off the mound.

"Well, it's kind of ironic, here San Diego is, and this is the club that made him break his hand," Johnson said. "Now, he's back on the mound. I hope he doesn't run in after and start hitting his locker again.

"But he threw great. Everybody was impressed who saw him throw."

Mattheus will throw off a mound at least a couple more times, and assuming no problems arise, he then would face Nationals hitters during batting practice. If that goes well, he would go on a rehab assignment, although Johnson doesn't think he would need much time.

"His main pitch is his sinker, and his arm strength is pretty good now," Johnson said. "He just has to build up some endurance in that shoulder."

Mattheus has been an important piece of the Nationals' bullpen. Before that outing in San Diego, he had a 2.35 ERA in 15 1/3 innings. In 115 career appearances, the 29-year-old owns a 3.14 ERA.

Andrew Simon is a reporter for MLB.com. Follow him on Twitter @HitTheCutoff. This story was not subject to the approval of Major League Baseball or its clubs.